Audio systems such as consumer electronic audio devices including desktop computers, laptop computers, pad computers, smart phones and digital media players have a headphone or earphone jack through which the portable device can interface with an accessory device, such as a directly powered headset. The typical headset may have a “Y” shape with two earbuds at the top of two wired lengths that have their bottom ends joined at the top of a common wire, the common wire having a plug for insertion or “plugging” into the jack at the other end. Each earbud has a speaker to provide audio output to the user's ears. The more recent headset may also have multiple integrated microphones located in the earbuds, along the wired lengths, and along the common wire to receive audio input from the user's mouth.
An audio integrated circuit referred to as an audio codec may be used within the audio device, to output audio to the headset when it is plugged into the headphone jack. In addition, the audio codec also includes the capability of receiving audio signals from the microphones. The audio codec is typically equipped with several such audio input and output channels, allowing audio to be played back through either earpiece and to be received from any of the microphones.
However, under typical environmental conditions, the microphones may do a poor job of capturing a sound of interest (e.g., speech received from a user's mouth) due to the presence of various background sounds. So, to address this issue many audio devices often rely on noise reduction, suppression, and/or cancellation techniques. One commonly used technique to improve signal to noise ratio is audio beamforming. Audio beamforming is a technique in which sounds received from two or more microphones are combined to enable the preferential capture of sound coming from certain directions. An audio device that uses audio beamforming can beamform using two or more closely spaced, omnidirectional microphones linked to a processor. The processor can then combine the signals captured by the different microphones to generate a single output to isolate a sound from background noise.